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Perfluoropolyethers (hereinafter PFPE) are fluids having important uses in oils and greases for use under extreme conditions. The three commercial PFPEs, KRYTOX (from E.I. du Pont de Nemours and Company, Inc., Wilmington Del.), FOMBLIN and GALDEN (from, Solvay Specialty Polymers, Milan, Italy) and DEMNUM (from Daikin Industries, Osaka, Japan) differ in chemical structure. A review of KRYTOX is found in Synthetic Lubricants and High-Performance Fluids, Rudnick and Shubkin, Eds., Marcel Dekker, New York, N.Y., 1999 (Chapter 8, pp. 215-237). A review of FOMBLIN and GALDEN is found in Organofluorine Chemistry, Banks et al., Eds., Plenum, New York, N.Y., 1994, Chapter 20, pp. 431-461, and for DEMNUM, in Organofluorine Chemistry (op. cit.), Chapter 21, pp. 463-467.
The anionic polymerization of hexafluoropropylene epoxide as described by Moore in U.S. Pat. No. 3,322,826 can be used to produce KRYTOX fluids. The resulting poly(hexafluoropropylene epoxide) PFPE fluids are hereinafter described as poly(HFPO) fluids.
The initial polymer has a terminal acid fluoride, which is hydrolyzed to the acid followed by fluorination. The structure of a poly(HFPO) fluid is shown by Formula 1:CF3—(CF2)2—O—[CF/(CF3)—CF2—O]s—RfI  (Formula 1)wherein s is an integer from 2-100 and RfI is CF2CF3 or CF(CF3)2, with the ratio of ethyl to isopropyl terminal group ranging from 20:1 to 50:1.
DEMNUM fluids are produced by sequential oligomerization and fluorination of 2,2,3,3-tetrafluorooxetane (tetrafluorooxetane), yielding the structure of Formula 2.F—[(CF2)3—O]t—RfII  (Formula 2)wherein RfII is CF3 or C2F5 and t is an integer from 2-200.
A common characteristic of the PFPE fluids is the presence of perfluoropropyl initial groups and perfluoroalkyl terminal groups.
Commonly, these perfluoroalkyl ethers can be modified by reacting the acid fluoride produced from the polymerization process. There is interest for functionalized perfluorinated polyethers and difunctional perfluorinated polyethers for uses such as lubricants, additives and catalysts. New initiators are needed to control the polymerization process to produce longer chain PFPEs. These compounds can also reduce costs by allowing for a continuous polymerization process using such initiators. There also is a need for new initiator systems for polymerization of these PFPEs. The present invention meets these needs.